Fuel-and-air control for internalcombustion engines



I De15,1942. L. F. G. BUTLER m. 2,30

FUEL-AND-AIR CONTROLS FOR INTERNAL-COMBUSTION ENGINES Filed May 20, 1940s Sheets-Sheet s Patented Dec. 15, 1942 FUEL-AND-AIR CONTROL FORINTERNAL- COMBUSTION ENGINES Leonard Frederick George Butler and RobertKelman Crowe, Bristol, England, assignors to The Bristol AeroplaneCompany Limited, Bristol, England, a British company Application May 20,1940, Serial No. 336,302 In Great Britain August 17, 1939 10; Claims.

This invention relates to fuel-and-air controls for internal-combustionengines and has for its object to maintain the proper ratio between themass of fuel and the mass of air admitted to the cylinders of. theengine despite variations in the density of the air in the inductionsystem of the engine. The invention is thusof particular application toaircraft engines: and, moreover, is primarily concerned with engines ofthe kind in whichliquid fuel is delivered either to the cylinders orinto the induction system near the cylinder-inlet ports by a meteringpump driven by the engine. Alternatively, the fuel may be injected intothe intake of a supercharging blower. I I

In order that the ratio between the mass of fuel and the mass of airadmitted to the engine v cylinder, shall have a predetermined value, itis necessary that the mass of fuel should be proportioned in relation tothe mass of the air taken into the cylinder during the induction strokeof the piston.

The mass of the air taken into the cylinder depends upon the pressureand temperature of the air supplied to the inlet ports and upon the massof residual gas remaining in the cylinder from the preceding powerstroke, which depends upon the back-pressure against which the exhaustgases are discharged. This back-pressure,

for a given design of engine and exhaust system. 1

will depend upon the circumambient atmospheric pressure.

According to one feature of the invention, means for automaticallymaintaining a predetermined ratio between the mass of fuel and the massof air admitted to the cylinder of an internal-combustion enginecomprises 'a temperature-responsive device exposed to the air deliveredto the cylinder, 9. pressure-responsive device exposed to the pressureof the air admitted to the cylinder, a pressure-responsive deviceexposed to the pressure of the circumambient atmosphere, and anoperative connection between the three said devices and means foradjusting the fuel-to-air ratio,. whereby a predetermined mixturestrength is automatically maintained despite the variables hereinbeforereferred to.

The ratio between the mass of the residual gas in the cylinder and themass of fresh air admitted depends not only upon the pressure of thecircumambient atmosphere but also upon the i pressure of the airadmitted to the cylinder. The pressure-responsive device exposed to theatmosphere and referred to above is therefore preferably exposed also tothe pressure of the air a admitted to the cylinder so as to respond tothe difference between these pressures. The pressure of the air admittedto the cylinder is not necessarily equal to, and will ordinarily differfrom the atmospheric pressure, particularly in the case of asupercharged engine. The pressure of the air admitted to' the cylinderis hereinafter termed the boost-pressure}? The temperature of the airadmitted to the cylinder is termed theboost-temperaturefif It is to beunderstood that the expression a predetermined mixture strength does notnecessarily mean that the mixture strength remains constant for allworking conditions of the engine. For example, it is found in aircraftengines that a comparatively rich mixture is desirable for idlingconditions and for conditions of maximum power, a weaker mixture beingmore suitable for intermediate or cruising conditions. Moreover, acontrol may be superimposed upon the automatic control in order toweaken the mixture during cruising conditions.

The degree of control required in respect of the residual gases isproportional to the unswept volume or compression space of the cylinderwhereas the degree of control required in respect of variations in theboost-pressure is proportional to the swept volume. Thepressure-responsive device exposed to the difference between theatmospheric pressure and the boostpressure is therefore so arranged,according to the invention, as to have an efiect, in relation 'to thedegree of control exerted by the responsive device exposed to theboost-pressure, which is equal to the ratio between the unswept andswept volume of the cylinder. Various means, whereby the necessarydifference between the effects of the two responsive devices isobtained, are described below.

According to another feature of the invention, a pressure-responsivedevice exposed to the boost-pressure may also constitute thepressureresponsive device of a servo-actuated throttlecontrol in which apressure-responsive device exposed to the boost-pressure is connectedthrough a relay to the engine throttle-valve so that, for agivendatum-setting of the pressure-responsive device, any departure of theengine boost-pressure from apredetermined value causes movement of thedevice which, through the relay, adjusts the position of thethrottle-valve whereby the boostepressure is corrected. The correctedboost-pressure acts upon the pressure-responsive device to restore itand the part of the relay it controls to their datum positions. Thedatum ternative to Figure 1 in which the apparatus inposition of thepressure-responsive device may be adjusted by a manually-operated cam orother means. Thus, for a given setting of the cam, the servo-controlmaintains a definite boost-pressure irrespective of the altitude atwhich the engine is operating, for all altitudes up to what is termedthe "rated altitude at and above which, at full-throttle, increase ofaltitude will produce a drop of boost-pressure.

According to another feature of the invention movements of thepressure-responsive device produced by changes of boost-pressure aretransmitted to the means for adjusting the mixture strength through afloating linkage.

According to another feature of the invention, the saidpressure-responsive device is connected at one end to one member of thelinkage and at the other end, through a resilient connection whichprovides lost-motion, to another member of the linkage and an abutmentobstructs the movement of the said member when the datum of the deviceis shifted so as to open the throttle. The consequent increase ofboost-pressure, after corporates a variable-datum boost-control,

Figure 5 is a section on the line 55 of Figure 4, to an enlarged scale,and

Figure 6 is a diagrammatic view showing the control unit coupled in theengine fuel system.

As shown first in Figure 1 the apparatus comprises a sealed casing IIIof suitable shape to enclose the parts hereinafter described, theinterior of the casing being connected through a union II to thedischarge side of the supercharging blower 2!. Thus, the atmospherewithin the casing is at a pressure which is always equal to theboost-pressure.

a short delay, restores the second member of the Y linkage, andtherefore the mixture-strength setting, to a position depending upon theboostpressure. The consequent relative movement between the two membersof the linkage which occurs before the boost-pressure has had time tobuild up to the value determined by the setting of the datum-varying camproduces an early enrichment, as is desirable during acceleration, andthe usual accelerator pump" is thus dispensed with. -The said abutmentis preferably intercomnected with the throttle-valve so as to beinoperative when the valve is fully open. Thus the automatic control ofmixture strength is maintained for all throttle conditions above therated altitude.

In view of the necessityfor exposing at least two pressure-responsivedevices to the boostpressure, the said devices, according to theinvention, are preferably enclosed within a sealed casing the interiorof which is connected to the engine induction system. To reduce to aminimum the number of external connections from the interior of the saidcasing, the casing may also include the linkage through which thepressure-responsive devices act upon a servo-motor which effectsadjustments of the mixture strength, and also the servo-motor itself.The said casing may also include the moving part of thtemperature-responsive device. Where, as above described, theboost-pressure responsive device also constitutes thepressure-responsive device of the servo-actuated throttle-control, thehydraulicrelay through-which the said device operates the throttle mayalso be contained in the same casing.

Alternatively, the linkages referred to may be situated outside thesealed casing.

Two specific embodiments of the invention will now be described, by wayof example, with reference to the accompanying diagrammatic drawings, ofwhich:

Figure 1 shows mixture-control apparatus, according to the invention,for use in conjunction with a supercharged aircraft engine in which thefuel is injected by metering pumps either into the cylinders or into theinduction pipes adjacent the inlet ports,

Figures 2 and 3 are diagrams showing alternative arrangements of theboostpressure capsule and atmospheric capsule,

Figure 4 is a diagram ofan arrangement al- The casing contains atemperature-capsule 12 the interior of which is connected by a capillarytube l3 to a phial M in the outlet conduit l5 from the superchargingblower. The capsule .I2 is an expansible receptacle anchored at its topend to the casing in. The capsule, capillary tube l3 and phial M arefilled with a suitable liquid such as alcohol, ether, or benzol so thatthe free lower end I6 of the capsule takes up a position which, at alltimes, corresponds to the boost temperature. The bottom end l6 of thetemperature capsul I2 is connected by a rod I! to a pin l8 carried byone arm l9 of a lever pivoted about an axle 20, the other arm 2| of thelever being pivoted at 22 to a link 23 of which the other end carries apin 24 which is constrained by means of suitable guides 25 to move in astraight horizontal line. The pin 24, which forms a fulcrum for a lever26, thus takes up a position in the guides 25 which at all timescorresponds to the boost temperature.

The casing Ill also contains an atmospheric capsule 21 the upper face ofwhich is anchored to the casing and the interior of which communicatesthrough a vent 28 with the circumambient atmosphere so that the bottomface 23 of the atmospheric capsule takes up a position corresponding tothe difierence between the atmospheric pressure within it and theboost-pressure outside it.

Connected by a short rod or link 30 to the lower face 29 of theatmospheric capsule 21 is a boost-pressure capsule 3| which is evacuatedso as to be influenced only by the boost-pressure by which it issurrounded. The capsules 21 and 3| may be of a resilient nature or theymay be provided with internal springs 32, 33, respectively.

As has already been explained, it is necessary that the effect of theatmospheric capsule 21 should be less than the efiect of theboostpressure capsule 3| in the same ratio as the ratio of the unsweptvolume of the engine cylinder to the swept volume. The necessary eifectmay be obtained, as shown in Figure l, by making the capsule 21 smallerthan the capsule 3| in the required ratio. For example, where the enginehas a compression ratio of '1, the boost-pressure capsule 3| may have avolume six times as great as that of the atmospheric capsule 21.Alternative arrangements are described below with reference to Figures 2and 3. In any event, the arrangement is such that a variation inboostpressure produces a displacement of the bottom end 34 of theboost-pressure capsule 3| which is greater than the displacementproduced by the same variation in the difference between atmosphericpressure and boost-pressure, by the same ratio as the ratio of the sweptvolume to the compression space. It will be seen that this ratio is I2,805,070 less by unity than the compression ratio of the engine.

The bottom 34 of the boost-pressure capsule 31 is connected to a rod 35to the lower end of which a pin 36 is afllxed to engage the forked end31 of the lever 26. This lever is slotted at 38 to engage the pin 24already described, and the other end of thelever is'pivoted at 39 to avertical sliding-rod 46 the upper end of which slides in a bore 4| andthe lower end in a bore 42, the bores being formed in integral parts ofthe casing and each being connected with the interior of the casing by aconduit 43, 44, respectively, to permit the rod 46 to slide freely inthem.

As has already been explained, the rod 35 moves in such manner that itsposition corresponds at all times to the absolute boost-pressure. Thefulcrum-pin 24 moves so that its position corresponds to the boosttemperature; the sliding-rod 46 therefore takes up a. position which atall times corresponds to the mass of fresh air contained in the enginecylinder at the end of the induction stroke.

At another point on the sliding-rod 49 it is connected by a pivot-pin 45to a. lever 46 which is slotted at 41 to engage a pin 48 on the upperend of a control-valve 49; the rod 46 is forked at its left-hand end 56to engage a pin 5| carried by the piston-rod 52 of a. hydraulic motor266 of which the piston 53 slides in a cylinder 54. The valve 49 haslands 55, 56, which co-operate with a pressure-port 51, drain-ports 58,59, and motor-ports 66, 6|, the ports 69 and 6| leading respectively tothe top and bottom of the motorcylinder 54. The piston-rod52 passes outof the casing'at the lower end and is connected by a mechanical linkage(not shown) to any known means for controlling the delivery-per-strokeof a fuel-injection pump or pumps.

' For stable conditions of operation the lands 55, 56, close the ports66 and 6| whereby the piston 53 remains stationary and is prevented frommoving by the oil or other hydraulic liquid contained in the cylinder54. ,If, for any. reason,

the boost temperature rises, the capsule. l2 expands, the lever l9, 2|,is rotatedin a counterclockwise direction, the pin 24 is moved to theright, the lever 26 rocks about thepin 36 so as follow-up movement ofthe lever 46 and valve 49 as already explained above. The piston 63,valve 49 and link 46 constitute a servo-motor of known form, follow-upmovements being transmitted from the piston to the valve by tiltingmovements of the lever 46 about the pin 45, whereby the motor-piston 53'assumes at all times a position corresponding to the positionof thesliding-rod 40.

Instead of connecting the atmospheric capsule 21 and the boost-pressurecapsule 3| together end-to-end, as shown in Figure 1, the capsules mayhave separate rods 65 and 66, as shown in Figure 2, each pivotallyconnected to one end of a floating link 61 of which the mid-point ispivoted by a pin 68 to the rod 35 of Figure 1. In Figure 2 the capsules3| and 21 have volumes of which the ratio is equal to the compressionratio of the engine minus one.

In yet another arrangement, as shown in Figure 3, the capsules 3| and 21may be identically similar so that the movement of the rod 55 due to achange in boost-pressure is equal to the movement of the rod 66 due to achange in the difference between boost-pressure and atmosphericpressure. In order that the displacement to raise the sliding-rod 49.The piston-rod 52 being held stationary for the time being, the lever 46rotates about the pin 5| so as toraise the valve 49. Consequently, theport 66 is opened to pressure oil from the port 51 and the port. 6| isplaced in communication with the; drain 59. The piston 53 is thereforedriven down, the mechanism to which it is connected being so arrangedthat downward movement of the piston decreases themass of fuel injectedper stroke so as to compensate for the decrease in density of of the rod66 shall be reduced in the required ratio with respect to movements ofthe rod 65, the operating-rod 35 is pivoted to the floating link 61 at apoint 69 which is six times as far from the right-hand end of the lever61 as it is from the left-hand end, assuming that the compression ratioof the engine is seven, as before. a In the alternative form of theinvention shown in Figures 4 and 5 the sealed casing I ll, boostpressureunion temperature-capsule l2 and hydraulic-motor 53, 54, are provided asbefore. The boost-capsule 3| however, is formed with two rods oneextending from each end. From its upper end a rod 16 extends through asuitable gland in the casing ID to constitute a tappet 1| which isspring-pressed upwardly against a datum-varying cam 12 by a compressionspring 13 ,Thle'cam is rotatable on a shaft 14 by means of a lever 15manually operable by the pilot. From the lower face of the capsule 3| arod 16 (termed the "valve-rod) extends downwardly to constitute thecontrolling valve 11 of a hydraulic relaycomprising a piston 18--reciprocable in a cylinder 19. The piston-rod 66 of the relay isconnected by suitable mechanism 8| to the constitute a servo-systemwhich operatesto mainthe air which the rise in temperature has caused.

Such downward movement of the piston 53 rocks the lever 46 about thepivot 45 so as to restore the valve 49 to the position shown in Figure 1in which the ports and 6| are closed. Conversely, a fall in the boosttemperature would cause the piston 53 to rise and thereby increase themass of fuel injected per stroke.

Any change in the density of thevair admitted to the engine cylindersresulting from a change in the altitude of flight or a change in thethrottle-opening similarly causes a suitable correction to theadjustment of the fuel pumps by rotation of the lever 26 about thefulcrum-pin 24 and the consequent movement of the valve 49,

tain constant the boost-pressure for any given setting of the cam 12.For example, if the boostpressure should fall, the capsule 3| willexpand, the rod 16 will move down, the valve 11 will open the motor-port89 to the pressure-port and the motor-port 88 to the drain-port 86 sothat the piston 18 will be driven upwardly. Such movement will betransmitted through the mechanism 6| to open the throttle-valve 82whereby the boost-pressure will be increased and the capsule 32collapsed to its original size, whereupon the valve 11 will be restoredto its original closed position. A different controlled boostpressure isobtainable at the will of the pilot by appropriate adjustment of thecam. However, at altitudes above what is termed the rated altitude ofthe engine, the boost-pressure ob- 'tainable at full throttle willdecrease with increase in altitude. The atmospheric capsule 21, in thismovement, is anchored to the casing by being fixed at its bottom face 29to a suitable lug or bracket 90. The top face is connected to a tube 9Iwhich extends through a suitable gland in the casing I0, the tube 9Iadmitting atmospheric pressure to the interior of the capsule 21. Thecapsules 3| and 21 are of such relative volume, or their springs are ofsuch rate, that the efiects of the two capsules bear the same ratio toone another as the ratio of the swept volume of the engine cylinder tothe unswept volume. Any of the methods above described ior ensuring thatthis ratio is obtained can be used in the arrangement of Figure 4.

A link 92 is pivoted to the tube SI and at its other end 93 is forked toengage a pin 94 on the tappet-rod 10. A similar link 95 extends betweenthe valve-rod 16 of the boost-pressure capsule 3I and a guide-rod 96which slides in a suitable bore in an integral part of the casing I0,the link 95 being connected to the guide-rod upon the relay-piston 53.

the rod I1 of the temperature-capsule is piv- 96 by a suitable pivot-pin91. In a manner explained below the guide-rod 99 is connected, through asuitable relay, to means for varying the mass of fuel injected into theengine cylinder or induction system. The mechanism has superimposed uponit the action of the temperaturecapsule I2 as in the case of Figure 1.The midpoints of the links 92 and 95 are interconnected by a thirdlink98.

The link 95 is not directly connected to the valve-rod 16 of theboost-pressure capsule but is formed with pins I00 to engage aperipheral groove IOI in a collar 99'which is slidable on the rod 15,being pressed downwardly by a compression spring I02, movement in thisdirection being limited by a flange I03 on the rod 16. An abutment I04(described more fully 'below) obstructs movement of the collar 99downwardly beyond a position corresponding to the closed position of thevalve 11, by engaging with a tooth I05 carried by the collar 99 as shownin Figure 5.

The'two links 92 and 95 are always approximately parallel with oneanother so that bodily movement of the boost-pressure capsule 3I ineither direction merely rocks the link 92 about the pivot on the tube 9|and the link 95 about the pivot 91. But expansion or contraction of theboost-pressure capsule rocks the links 92 and 95 with respect to oneanother whereby the guide-rod 96 is moved up or down, the altitudecapsule 91 constituting the abutment for such movement.

When the datum-varying cam 12 is adjusted in such sense as to increasethe throttle-opening,

As is known, such enrichment of the mixture strength during accelerationis desirable and the arrangement above described has the advantage,already explained, of enabling the usual "accelorator pump to bedispensed with.

Any convenient arrangement may be used for imposing the effect of thetemperature-capsule As shown in Figure 4,

oted at I05 to a lever I06 rotatable on a fixed axle I01 and formed withan arcuate slot I08. The slot co-operates with a pin I09 carried on aswinging link 0 pivoted at III to a fixed part H2. The lower end of thelink IIO carries a pin II3 engaging a slot H4 in a lever H5, thelefthand end of which is pivoted at II6 to the guiderod 95. Theright-hand end of the lever II5 is forked at II1 to engage a pin II8 ona slidingrod I I9 which operates in exactly the same manner as thesliding-rod 40 of Figure 1, being pivoted to the follow-up lever 46 ofthe hydraulic relay which comprises a control-valve 4'9 and thenecessary ports and conduits already described with reference toFigure 1. may operate a lever I20 which controls a cam I2I and followerI22 such that movements of the follower towards the left increases thesupply of fuel and vice versa.

It will be understood that the angular position of the link H0, and thusthe position of the fulcrum-pin H3, depends upon the boost temperature.As explained above, the vertical position of the guide-rod 96corresponds to the pressure of the air existing in the engine cylinderat the end of the induction stroke and thus the sliding-rod H9 andrelay-piston 53 always assume positions corresponding to the mass of thefresh air existing in the engine cylinder at the end of the inductionstroke.

The abutment I04, above referred to, is constituted by the end of alever I23 having an axle I24 borne in the casing I0 as shown in Figure5. The other end of the lever engages by a pin-andslot connection I25with the piston-rod 80. The portion I04 is of such shape that when thepiston I8 is at its uppermost position, corresponding to fullthrottle-opening, the tooth I 05 is free to move down with the rod 16under the action of the spring I02. It will be understood that, forconditions above the rated altitude of the engine,

the follow-up action of the boost-pressure capsule 3| on the valve 11 issuspended when the throttle is fully open since the boost-pressurecannot be increased to such value as would restore the parts to theposition shown in Figure 4. Thus, the valve 11 can assume a position inwhich the underside of the piston 18 is permanently open topressure-liquid. In this condition of the parts, if the abutment I04were to remain operative upon the tooth I05, the disproportionateenrichment of the mixture strength above referred to would becontinuously maintained. By rendering the abutment automaticallyinoperative as above described, the automatic control of mixturestrength is maintained for all throttle conditions including throttleconditions above the rated altitude.

It may be necessary to compensate for the difference which occursbetween the temperature of the air delivered by the supercharger to thecylinder and the temperature of the air in the cylinder at the end ofthe induction stroke. If so, the temperature-capsule I2 may beinterconnected with the fulcrum-pin 24 (Figure 1) or II3 (Figure 4)through the intermediary of suitable cam-mechanism. For example, theslot I08 in Figure 4 may be so designed as to provide the necessarycompensation. V

In each of the embodiments above described.

the desired fuel-to-air ratio for each working The piston-rod 52 and themass of air admitted to the cylinder of an internal-combustion engine,comprising a temperature-responsive device exposed to the air deliveredto the cylinder, a pressure-responsive device exposed to the pressure ofthe air admitted to the cylinder, a pressure-responsive device exposedto the diiference between the atmospheric pressure and theboost-pressure and so arranged as to have an eifect, in relation to thedegree of control exerted by the responsive device exposed totheboost-pressure alone, which is equal to the ratio between the unsweptand swept volumes of the cylinder, means for' adjusting the fuel-toairratio and an operative connection between said temperature-responsivedevice, said pressure-responsive devices and said adjusting means.

2,.Apparatus for automatically maintaining apredetermined ratio betweenthe mass of fuel and the mass of air admitted to the cylinder of aninternal-combustion engine, comprising a temperature-responsive deviceexposed to the air delivered to the cylinder, a pressure-responsivedevice exposed to the pressure of the air admitted to the cylinder, apressure-responsive device exposed to the pressure of the atmosphere,means for adjusting the fuel-to-air ratio, an operative connectionbetween the three said devices and the said adjusting means, and aservo-operated throttle-control of which the pressure-responsive deviceis constituted by sponsive device. I

3. Apparatus for automatically maintaining a predetermined ratio betweenthe mass of fuel and the mass of air admitted to the cylinder of thefirst said pressure-rean intemal-combustion engine, comprising atemperature-responsive device exposed to the air delivered to thecylinder, a pressure-responsive device exposed to the boost-pressure, apressureresponsive device exposed to the difierence between theatmospheric pressure and the boostpressure, means for adjusting thefuel-to-air ratio, and an operative connection between the three saiddevices and the said adjusting means and a sealed casing pressure withinwhich is maintained by the boost-pressure of the engine, the saidpressure-responsive devices being enclosured within the said casing.

4. Apparatus for automatically maintaining a predetermined ratio betweenthe mass of fuel and the mass of air admitted to the cylinder of asupercharged aero engine comprising a supercharging blower, a sealedcasing, a conduit connecting said casing to the discharge side of thesupercharging blower, a temperature. capsule (with one end fixed in saidcasing) the temperature-responsive element of which is disposed in thedischarge of the supercharging blower, an atmospheric capsulewith oneend fixed in said casing, a conduit connecting said capsule with theatmosphere, a boost pressure capsule disposed within said casing, alinkage operatively connected to the moving parts of each of the threecapsules, adjusting means for controlling fuel delivery to the engineand an operative connection between the said linkage and said adjustingmeans.

5. Apparatus for automatically maintaining a predetermined ratio betweenthe mass of fuel and the mass of air admitted to the cylinder of asupercharged aero engine comprising a super charging blower, a sealedcasing, a conduit connecting" said casing tothe discharge side of thesupercharging blower, a temperature capsule (with one end fixed in saidcasing) the temperature-responsive element of which is disposed in thedischarge of the supercharging blower, an atmospheric capsule with oneend fixed in said casing, a conduit connecting said capsule with theatmosphere, a boost pressure capsule disposed within'said casing, alinkage operatively connected to the moving parts of each of the threecapsules, adjusting means for controlling fuel delivery to the engine,an operative connection between the said linkage and said adjustingmeans and a servo-operated throttle control of which thepressure-responsive device is constituted by the said boost pressurecapsule.

6. In combination, a control means for the fuel-injection pump of aninternal combustion engine, temperature-response means subject to theair constituent, density-response means also subject to the airconstituent, and connections between said temperature and densityresponse means and the control means including a common member coupledat oneside positively to the control means and at the other side looselyto both response means independently.

7. In combination, a control means for the fuel-injection pump of aninternal combustion engine, temperature-response means subject to theair constituent, density-response means also subject to the airconstituent, and connections between said temperature anddensity-response means and the control means including a common levercoupled at one side positively to the control means, lost-motioncouplings between said connections and said lever to enable theoperation of the control device through said lever independently fromeither of said connections.

8. In'combination, a control means for the fuel-injection pump ofaninternal combustion engine, temperature-response means subjectto theair constituent, density-response means also subject to the airconstituent, connections between said temperature and density responsemeans and the control means including a lever coupled at one sidepositively to the control means, lost motion couplings between saidconnections and said lever acting as variable fulcrums for the levercoacting conjointly to shift either fulcrum independently by itsrespective response means and thereby alter the effective throw of thelever in its operation by the other response means.

9. In combination, a control means for the fuel injection pump of aninternal combustion engine, density-response means subject to the airconstituent, atmospheric-response means, and connections between saiddensity and atmospheric response means and the control means soconstructed and arranged that the control means is operable from eitherresponse means independently of the other response means, datum-varyingmeans for shifting said densityresponse means with reference toits'connection, said last mentioned connection being loosely c0nnectedto said density-response means.

Ewin

between the density and atmospheric response 10 means and the throttlevalve control means, said connections having a loose coupling to thedensity-response means, resilient means for taking up normally saidloose coupling, and datum varying means for shitting saiddensity-response means in respect to said loose coupling.

LEONARD FREDERICK GEORGE BUTLER. ROBERT miLMAN CROWE.

